found this lone cup (unmarked except for made in new zealand) then some days later came across what must have been the rest of the set (for $40!) in the same shop, so my cup must have been a stray. Couldn't get a photo of the backstamp (which was rather pretty) but copied the details down.

It has the same (or similar, perhaps slightly 'bluer') speckled pale blue background as another cup I found this year, the "Delicate Roses on Pale Blue with Mustard Speckle". Same shape cup too, so maybe made at around the same time. Just wish I could have got the backstamp - must get a camera phone!